This wall is created by the Totem of Protection at the center of your settlement. The Totem does not allow other players to enter your territory, but it has to restore its energy from time to time. During that period you are vulnerable for attacks from other players.

After each participation in a raid, the Totem activates for 48 hours. An Orb of Protection can immediately add 24 hours to the time remained before the cooldown of the Totem.